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207 lines
7.1 KiB
Markdown
207 lines
7.1 KiB
Markdown
# spdlog
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Very fast, header only, C++ logging library. [](https://travis-ci.org/gabime/spdlog) [](https://ci.appveyor.com/project/gabime/spdlog)
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## Install
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Just copy the source [folder](https://github.com/gabime/spdlog/tree/master/include/spdlog) to your build tree and use a C++11 compiler
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## Platforms
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* Linux (gcc 4.8.1+, clang 3.5+)
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* Windows (visual studio 2013+, cygwin/mingw with g++ 4.9.1+)
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* Mac OSX (clang 3.5+)
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* Solaris (gcc 5.2.0+)
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* Android
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##Features
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* Very fast - performance is the primary goal (see [benchmarks](#benchmarks) below).
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* Headers only, just copy and use.
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* Feature rich [call style](#usage-example) using the excellent [fmt](https://github.com/fmtlib/fmt) library.
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* Extremely fast asynchronous mode (optional) - using lockfree queues and other tricks to reach millions of calls/sec.
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* [Custom](https://github.com/gabime/spdlog/wiki/3.-Custom-formatting) formatting.
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* Multi/Single threaded loggers.
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* Various log targets:
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* Rotating log files.
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* Daily log files.
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* Console logging (colors supported).
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* syslog.
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* Easily extendable with custom log targets (just implement a single function in the [sink](include/spdlog/sinks/sink.h) interface).
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* Severity based filtering - threshold levels can be modified in runtime as well as in compile time.
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## Benchmarks
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Below are some [benchmarks](bench) comparing popular log libraries under Ubuntu 64 bit, Intel i7-4770 CPU @ 3.40GHz
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#### Synchronous mode
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Time needed to log 1,000,000 lines in synchronous mode (in seconds, the best of 3 runs):
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|threads|boost log 1.54|glog |easylogging |spdlog|
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|-------|:-------:|:-----:|----------:|------:|
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|1| 4.169s |1.066s |0.975s |0.302s|
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|10| 6.180s |3.032s |2.857s |0.968s|
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|100| 5.981s |1.139s |4.512s |0.497s|
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#### Asynchronous mode
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Time needed to log 1,000,000 lines in asynchronous mode, i.e. the time it takes to put them in the async queue (in seconds, the best of 3 runs):
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|threads|g2log <sup>async logger</sup> |spdlog <sup>async mode</sup>|
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|:-------|:-----:|-------------------------:|
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|1| 1.850s |0.216s |
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|10| 0.943s |0.173s|
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|100| 0.959s |0.202s|
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## Usage Example
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```c++
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#include "spdlog/spdlog.h"
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#include <iostream>
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#include <memory>
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void async_example();
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void syslog_example();
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void user_defined_example();
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void err_handler_example();
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namespace spd = spdlog;
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int main(int, char*[])
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{
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try
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{
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// Console logger with color
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auto console = spd::stdout_color_mt("console");
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console->info("Welcome to spdlog!");
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console->error("Some error message with arg{}..", 1);
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// Formatting examples
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console->warn("Easy padding in numbers like {:08d}", 12);
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console->critical("Support for int: {0:d}; hex: {0:x}; oct: {0:o}; bin: {0:b}", 42);
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console->info("Support for floats {:03.2f}", 1.23456);
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console->info("Positional args are {1} {0}..", "too", "supported");
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console->info("{:<30}", "left aligned");
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spd::get("console")->info("loggers can be retrieved from a global registry using the spdlog::get(logger_name) function");
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// Create basic file logger (not rotated)
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auto my_logger = spd::basic_logger_mt("basic_logger", "logs/basic.txt");
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my_logger->info("Some log message");
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// Create a file rotating logger with 5mb size max and 3 rotated files
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auto rotating_logger = spd::rotating_logger_mt("some_logger_name", "logs/mylogfile", 1048576 * 5, 3);
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for (int i = 0; i < 10; ++i)
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rotating_logger->info("{} * {} equals {:>10}", i, i, i*i);
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// Create a daily logger - a new file is created every day on 2:30am
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auto daily_logger = spd::daily_logger_mt("daily_logger", "logs/daily", 2, 30);
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// trigger flush if the log severity is error or higher
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daily_logger->flush_on(spd::level::err);
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daily_logger->info(123.44);
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// Customize msg format for all messages
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spd::set_pattern("*** [%H:%M:%S %z] [thread %t] %v ***");
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rotating_logger->info("This is another message with custom format");
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// Runtime log levels
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spd::set_level(spd::level::info); //Set global log level to info
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console->debug("This message shold not be displayed!");
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console->set_level(spd::level::debug); // Set specific logger's log level
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console->debug("This message shold be displayed..");
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// Compile time log levels
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// define SPDLOG_DEBUG_ON or SPDLOG_TRACE_ON
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SPDLOG_TRACE(console, "Enabled only #ifdef SPDLOG_TRACE_ON..{} ,{}", 1, 3.23);
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SPDLOG_DEBUG(console, "Enabled only #ifdef SPDLOG_DEBUG_ON.. {} ,{}", 1, 3.23);
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// Asynchronous logging is very fast..
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// Just call spdlog::set_async_mode(q_size) and all created loggers from now on will be asynchronous..
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async_example();
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// syslog example. linux/osx only
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syslog_example();
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// android example. compile with NDK
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android_example();
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// Log user-defined types example
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user_defined_example();
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// Change default log error handler
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err_handler_example();
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// Apply a function on all registered loggers
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spd::apply_all([&](std::shared_ptr<spdlog::logger> l)
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{
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l->info("End of example.");
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});
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// Release and close all loggers
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spdlog::drop_all();
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}
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// Exceptions will only be thrown upon failed logger or sink construction (not during logging)
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catch (const spd::spdlog_ex& ex)
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{
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std::cout << "Log init failed: " << ex.what() << std::endl;
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return 1;
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}
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}
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void async_example()
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{
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size_t q_size = 4096; //queue size must be power of 2
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spdlog::set_async_mode(q_size);
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auto async_file = spd::daily_logger_st("async_file_logger", "logs/async_log.txt");
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for (int i = 0; i < 100; ++i)
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async_file->info("Async message #{}", i);
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}
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//syslog example
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void syslog_example()
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{
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#ifdef SPDLOG_ENABLE_SYSLOG
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std::string ident = "spdlog-example";
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auto syslog_logger = spd::syslog_logger("syslog", ident, LOG_PID);
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syslog_logger->warn("This is warning that will end up in syslog..");
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#endif
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}
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// user defined types logging by implementing operator<<
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struct my_type
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{
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int i;
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template<typename OStream>
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friend OStream& operator<<(OStream& os, const my_type &c)
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{
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return os << "[my_type i="<<c.i << "]";
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}
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};
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#include <spdlog/fmt/ostr.h> // must be included
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void user_defined_example()
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{
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spd::get("console")->info("user defined type: {}", my_type { 14 });
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}
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//
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//custom error handler
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//
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void err_handler_example()
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{
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spdlog::set_error_handler([](const std::string& msg) {
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std::cerr << "my err handler: " << msg << std::endl;
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});
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// (or logger->set_error_handler(..) to set for specific logger)
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}
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```
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## Documentation
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Documentation can be found in the [wiki](https://github.com/gabime/spdlog/wiki/1.-QuickStart) pages.
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